Codec-specific handover thresholds

Abstract

A handover procedure can be implemented using a codec-specific threshold as a triggering event for the handover procedure. A mobile device can initiate a communication session with a serving access point (AP). The mobile device can receive a codec established for the communication session, access a set of codec-specific thresholds stored in memory of the mobile device to determine a handover triggering threshold that is specific to the codec used for the communication session. The mobile device can measure a parameter of a radio signal from the serving AP, and when the measured parameter falls below the codec-specific threshold, a handover procedure can be initiated to transition the communication session to a target AP.

We claim: 
     
       1. A computer-implemented method comprising:
 sending, by a mobile device, a registration message to a serving access point (AP) configured to provide access to an Internet Protocol (IP) Multimedia Subsystem (IMS) core; 
 sending, by the mobile device, a message to the serving AP for initiating a communication session; 
 receiving, at the mobile device, a selected codec for the communication session; 
 accessing, by the mobile device and from memory of the mobile device, a data structure that maintains a first codec-specific threshold in association with a first codec and a second codec-specific threshold in association with a second codec, wherein the first codec-specific threshold and the second codec-specific threshold are different thresholds; 
 comparing, by the mobile device, the selected codec to the first codec stored in the memory of the mobile device; 
 determining, by the mobile device, that the selected codec corresponds to the first codec; 
 measuring a parameter of a radio signal from the serving AP to obtain a radio signal measurement; 
 determining that the radio signal measurement is below the first codec-specific threshold associated with the first codec; and 
 transitioning the communication session from the serving AP to a target AP in communication range of the mobile device, the target AP configured to provide access to the IMS core. 
 
     
     
       2. The computer-implemented method of  claim 1 , wherein:
 the data structure comprises a lookup table; 
 the first codec-specific threshold and the second codec-specific threshold are maintained in the lookup table that associates the first codec with the first codec-specific threshold and the second codec with the second codec-specific threshold; and 
 comparing the selected codec to the first codec is performed by a lookup operation in the lookup table. 
 
     
     
       3. The computer-implemented method of  claim 2 , wherein the serving AP comprises a cellular base station, the method further comprising, in response to sending the registration message:
 receiving, from the cellular base station, a system information block including the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec; and 
 storing the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec in the lookup table. 
 
     
     
       4. The computer-implemented method of  claim 1 , further comprising:
 scanning, by a WiFi radio of the mobile device, for WiFi APs in the communication range of the mobile device; and 
 for each WiFi AP of the WiFi APs, measuring the parameter of a radio signal from the WiFi AP to obtain an additional radio signal measurement, 
 wherein the target AP comprises a WiFi AP of the WiFi APs having a highest radio signal measurement of the additional radio signal measurements associated with the WiFi APs. 
 
     
     
       5. The computer-implemented method of  claim 1 , further comprising:
 scanning, by a cellular radio of the mobile device, for cellular base stations in the communication range of the mobile device; and 
 for each cellular base station of the cellular base stations, measuring the parameter of a radio signal from the cellular base station to obtain an additional radio signal measurement, 
 wherein the target AP comprises a cellular base station of the cellular base stations having a highest radio signal measurement of the additional radio signal measurements associated with the cellular base stations. 
 
     
     
       6. The computer-implemented method of  claim 1 , wherein transitioning the communication session from the serving AP to the target AP comprises:
 measuring the parameter of individual radio signals of multiple radio signals from multiple candidate target APs to obtain multiple radio signal measurements for the multiple candidate target APs, the multiple candidate target APs including the target AP; 
 determining, by the mobile device, that the target AP is associated with a highest radio signal measurement of the multiple radio signal measurements; 
 sending, by the mobile device, a second registration message to the target AP; 
 establishing the communication session served by the target AP; and 
 terminating the communication session with the serving AP. 
 
     
     
       7. The computer-implemented method of  claim 1 , wherein:
 the first codec, the second codec, and the selected codec comprise audio codecs; and 
 the communication session comprises a voice communication session. 
 
     
     
       8. A mobile device comprising:
 a processor; 
 one or more radio chips; and 
 memory storing computer-executable instructions that, when executed by the processor, cause the mobile device to perform operations comprising:
 initiating, via the one or more radio chips, a communication session over an Internet Protocol (IP) Multimedia Subsystem (IMS) core using a selected codec and a serving access point (AP) for the communication session; 
 accessing, from the memory of the mobile device, a data structure that maintains a first codec-specific threshold in association with a first codec and a second codec-specific threshold in association with a second codec, wherein the first codec-specific threshold and the second codec-specific threshold are different thresholds; 
 comparing the selected codec to the first codec stored in the memory of the mobile device; 
 determining that the selected codec corresponds to the first codec; 
 measuring, via the one or more radio chips, a parameter of a radio signal from the serving AP to obtain a radio signal measurement; 
 determining that the radio signal measurement is below the first codec-specific threshold associated with the first codec; and 
 transitioning, via the one or more radio chips, the communication session from the serving AP to a target AP in communication range of the mobile device. 
 
 
     
     
       9. The mobile device of  claim 8 , wherein:
 the memory further stores the data structure as a lookup table for maintaining mappings between codec-specific thresholds and corresponding codecs, 
 the mappings including the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec; and 
 comparing the selected codec to the first codec comprises performing a lookup operation in the lookup table using the selected codec. 
 
     
     
       10. The mobile device of  claim 8 , wherein the serving AP comprises a cellular base station and the one or more radio chips include a cellular radio chip, the operations further comprising, prior to storing, in the memory of the mobile device, the data structure that maintains the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec:
 sending, via the cellular radio chip, a registration message to the cellular base station; and 
 receiving, via the cellular radio chip and from the cellular base station, a system information block including the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec. 
 
     
     
       11. The mobile device of  claim 8 , wherein the one or more radio chips include a WiFi radio chip, the operations further comprising:
 scanning, via the WiFi radio chip, for WiFi APs in the communication range of the mobile device; and 
 for each WiFi AP of the WiFi APs, measuring, via the WiFi radio chip, the parameter of a radio signal from the WiFi AP to obtain an additional radio signal measurement, 
 wherein the target AP comprises a WiFi AP of the WiFi APs having a highest radio signal measurement of the additional radio signal measurements associated with the WiFi APs. 
 
     
     
       12. The mobile device of  claim 8 , wherein the one or more radio chips include a cellular radio chip, the operations further comprising:
 scanning, via the cellular radio chip, for cellular base stations in the communication range of the mobile device; and 
 for each cellular base station of the cellular base stations, measuring, via the cellular radio chip, the parameter of a radio signal from the cellular base station to obtain an additional radio signal measurement, 
 wherein the target AP comprises a cellular base station of the cellular base stations having a highest radio signal measurement of the additional radio signal measurements associated with the cellular base stations. 
 
     
     
       13. The mobile device of  claim 8 , wherein transitioning the communication session from the serving AP to the target AP comprises:
 measuring, via the one or more radio chips, the parameter of individual radio signals of multiple radio signals from multiple candidate target APs to obtain multiple radio signal measurements for the multiple candidate target APs, the multiple candidate target APs including the target AP; 
 determining that the target AP is associated with a highest radio signal measurement of the multiple radio signal measurements; 
 sending, via the one or more radio chips, a second registration message to the target AP; 
 establishing, via the one or more radio chips, the communication session served by the target AP; and 
 terminating, via the one or more radio chips, the communication session with the serving AP. 
 
     
     
       14. The mobile device of  claim 8 , wherein:
 the first codec, the second codec, and the selected codec comprise audio codecs; and 
 the communication session comprises a voice communication session. 
 
     
     
       15. The mobile device of  claim 8 , wherein the parameter comprises at least one of a reference signal received power (RSRP) parameter or a reference signal received quality (RSRQ) parameter. 
     
     
       16. The mobile device of  claim 8 , the operations further comprising:
 receiving, at the mobile device, a new selected codec for the communication session served by the target AP; 
 after completing a handover to the target AP:
 accessing, from memory of the mobile device, the data structure; 
 comparing the new selected codec to the second codec stored in the memory of the mobile device; 
 determining that the new selected codec corresponds to the second codec; 
 measuring the parameter of a radio signal from the target AP to obtain an additional radio signal measurement; 
 determining that the additional radio signal measurement is below the second codec-specific threshold associated with the second codec; and 
 transitioning the communication session from the target AP to a new target AP in the communication range of the mobile device, the new target AP configured to provide access to the IMS core. 
 
 
     
     
       17. One or more non-transitory computer-readable storage media of a mobile device, the one or more non-transitory computer-readable storage media storing computer-executable instructions that, when executed by one or more processors of the mobile device, cause the mobile device to perform operations comprising:
 initiating, via one or more radio chips of the mobile device, a communication session over an Internet Protocol (IP) Multimedia Subsystem (IMS) core using a selected codec and a serving access point (AP) for the communication session; 
 accessing, from the one or more non-transitory computer-readable storage media of the mobile device, a data structure that maintains a first codec-specific threshold in association with a first codec and a second codec-specific threshold in association with a second codec, wherein the first codec-specific threshold and the second codec-specific threshold are different thresholds; 
 comparing the selected codec to the first codec stored in the one or more non-transitory computer-readable storage media of the mobile device; 
 determining that the selected codec corresponds to the first codec; 
 measuring, via the one or more radio chips, a parameter of a radio signal from the serving AP to obtain a radio signal measurement; 
 determining that the radio signal measurement is below the first codec-specific threshold associated with the first codec; and 
 transitioning, via the one or more radio chips, the communication session from the serving AP to a target AP in communication range of the mobile device. 
 
     
     
       18. The one or more non-transitory computer-readable storage media of  claim 17 , wherein:
 the one or more non-transitory computer-readable storage media further stores the data structure as a lookup table for maintaining mappings between codec-specific thresholds and corresponding codecs, the mappings including the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec; and 
 comparing the selected codec to the first codec comprises performing a lookup operation in the lookup table using the selected codec. 
 
     
     
       19. The one or more non-transitory computer-readable storage media of  claim 17 , wherein the serving AP comprises a cellular base station and the one or more radio chips include a cellular radio chip, the operations further comprising, prior to storing, in the one or more non-transitory computer-readable storage media of the mobile device, the data structure that maintains the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec:
 sending, via the cellular radio chip, a registration message to the cellular base station; and 
 receiving, via the cellular radio chip and from the cellular base station, a system information block including the first codec-specific threshold in association with the first codec and the second codec-specific threshold in association with the second codec. 
 
     
     
       20. The one or more non-transitory computer-readable storage media of  claim 17 , wherein the one or more radio chips include a WiFi radio chip, the operations further comprising:
 scanning, via the WiFi radio chip, for WiFi APs in the communication range of the mobile device; and 
 for each WiFi AP of the WiFi APs, measuring, via the WiFi radio chip, the parameter of a radio signal from the WiFi AP to obtain an additional radio signal measurement, 
 wherein the target AP comprises a WiFi AP of the WiFi APs having a highest radio signal measurement of the additional radio signal measurements associated with the WiFi APs. 
 
     
     
       21. The one or more non-transitory computer-readable storage media of  claim 17 , wherein the one or more radio chips include a cellular radio chip, the operations further comprising:
 scanning, via the cellular radio chip, for cellular base stations in the communication range of the mobile device; and 
 for each cellular base station of the cellular base stations, measuring, via the cellular radio chip, the parameter of a radio signal from the cellular base station to obtain an additional radio signal measurement, 
 wherein the target AP comprises a cellular base station of the cellular base stations having a highest radio signal measurement of the additional radio signal measurements associated with the cellular base stations.